论文部分内容阅读
对巫溪地区田坝剖面五峰组—龙马溪组底部30件页岩样品开展了有机碳含量、微量元素地球化学等方面研究,分析了不同层段有机质富集特征及其控制因素,认为海平面升降控制着水体缺氧程度,从而影响该区有机质沉积富集程度.研究结果表明:1)五峰组—龙马溪组底部页岩中共识别出4个有机质沉积阶段,总有机碳(TOC)含量整体较高,TOC平均达到3.7%,但与古生产力(生源钡Babio含量)相关性不明显,指示着古生产力总体上不是该时期有机质沉积的主控因素;2)尽管不同有机质沉积阶段的水体氧化还原条件具有一定差异性,但与TOC变化总体上具有相关性,这表明这些时期有机质沉积主要受控于缺氧程度,其富集机理属于“保存模式”;3)五峰组—龙马溪组早期有机质沉积模式为:海平面的升降控制着沉积水体的缺氧程度,海平面下降造成底水富氧,上升形成底水缺氧,从而控制着页岩中有机质富集程度.
The organic carbon content and trace element geochemistry of 30 shale samples at the bottom of Wufeng-Longmaxi Formation in Tianba section of Wuxi area were studied. The characteristics of enrichment of organic matter in different layers and their controlling factors were analyzed. It is concluded that the sea level The results show that: (1) Four organic matter depositional stages are identified in the shale at the bottom of the Wufeng-Longmaxi Formation, with the total organic carbon (TOC) content as a whole While the TOC averaged 3.7%. However, the correlation between paleoclimate and barium content was insignificant, indicating that the paleo-productivity was not the main controlling factor of organic matter deposition during this period. (2) Although the oxidation of water bodies in different organic matter deposition stages The results show that the organic matter deposition in these periods is mainly controlled by the degree of anoxia, and its enrichment mechanism belongs to “preservation mode ”; 3) Wufeng group - Longmaxi The early organic deposition model of the group is as follows: the sea-level rise and fall control the hypoxia level of the sedimentary water body, the sea level is reduced and the bottom water is enriched with oxygen, rising to form the bottom water anoxia, thus controlling Rocks degree of enrichment of organic matter.